A Comparison of the Physico-Chemical and Bacteriological Quality of Greywater from Water Deficient Households in Homabay Town and Githurai Estates in Kenya

Abstract

Greywater, the untreated household wastewater that has not been contaminated by toilet waste, has been touted as a reliable all year-round source of water, especially in water scarce areas. Although it is commonly reused in water scarce urban and peri-urban settlements in Kenya, information on its bacteriological and physico-chemical properties is generally limited. The present study sought to compare the physico-chemical and bacteriological quality of kitchen and laundry greywater from an urban (Githurai) and peri-urban settlement (Homabay). Compared to the source water, kitchen and laundry greywater at the two sites had higher electrical conductivity (EC) and salinity, depressed dissolved oxygen (DO) levels and a wide pH range. Although significant differences in EC, DO and salinity of greywater from kitchen and laundry were noted (P < 0.05), the two sites differed significantly only in DO (P = 0.002). Total coliforms (TC) and fecal coliforms (FC) were also higher in greywater than in source water. The greywater types differed in TC (P = 0.003) while the two sites differed in both TC and FC (P 0.03). High loads of TC and FC suggest possible fecal contamination of greywater. This coupled with the occasional presence of Salmonella, Shigella and Vibrio cholerae means that reuse of untreated greywater is not safe in both sites, and should be treated before use. Owing to the differences in the quality of the different types of greywater as well as the sites investigated, the design of greywater treatment technologies should consider both type and source.

Human Mitochondrial DNA and Endogenous Bacterial Surrogates for Risk Assessment of Graywater Reuse

“…Sources can include dishwashing, shower, bath, laundry, and sink water; of these, the most abundant by volume is laundry . Recycling domestic graywater can assist water distribution systems by creating a decentralized water source capable of reducing potable demand on stressed supplies in arid regions, during periods of water shortage, and where population increase outpaces available supplies. , However, due to varying but significant levels of traditional wastewater parameters such as COD, BOD, TSS, VSS, turbidity, pH, and electrical conductivity, − graywater quality has been described as containing contaminants between that of raw wastewater and secondary effluent . In addition, opportunistic and/or enteric bacterial, viral, and protozoan pathogens have been found in graywater, − suggesting a health risk for reuse of untreated graywater.…”

Quantitative Microbial Risk Analysis for Various Bacterial Exposure Scenarios Involving Greywater Reuse for Irrigation

“…Salmonella enterica is a common pathogen associated with food handling in kitchen wastewater that might, on rare occasion, be included in greywater-reuse schemes. Shigella is an opportunistic pathogen that has been found in previous studies in treated greywater [9,10,27]. Salmonella enterica and Shigella spp.…”

Bacterial diversity in the waterholes of the Kruger National Park: an eDNA metabarcoding approach

“…The two waterholes in Kingfisherspruit are fed in part with greywater that is passed through reed beds. Greywater is untreated household wastewater that typically has not been contaminated by toilet waste and is often used as year-round sources of water, especially in water scarce areas (Nganga et al 2012). Compared to source water, kitchen and laundry greywater can have elevated conductivity (Nganga et al 2012), which may explain the high conductivity of water at these sites, and present a strong selective environment driving their unique bacterial communities.…”